For the stuff that is not physical I tell my kids it’s good practice for learning not to let someone, who is obviously having a bad day or worse, push their buttons. It bothers me more that classroom time is disrupted by lousy students acting out.
Most the physical stuff is petty and will not escalate unless two want to quarrel. It seems scary perhaps, but it is nothing to go kung fu fighting about. Pretty soon your kid will go around being a nuisance,posturing karate kid before anyone even does anything to her. It’s not about being pacifist, its about knowing when to react and when not to worry. Kindergarten is pretty safe even in the ghetto and you ain’t in the ghetto.